Collie Eye Anomaly (CEA)
Collie eye anomaly (CEA) is an autosomal recessive hereditary disorder of eye development that results from a mutation in the NHEJ1 gene. The effects of this mutation are quite variable. Some affected dogs exhibit no apparent visual impairment while others are completely blind. In moderate cases dogs may have poor vision characterized by hesitancy in navigating stairs, bumping into objects, and having difficulty navigating in changed or unfamiliar surroundings. The basis for this variability in disease severity associated with the same mutation is not understood. Dogs with mild signs can produce puppies with severe CEA.
Most affected dogs have choroidal hypoplasia, an underdevelopment of a layer of large blood vessels behind the retina. Affected dogs may also present with small eyeballs, mineralization of the cornea, bleeding inside the eye, detachment of the retina, or holes in the retina. Diagnosis can be made by an ophthalmologist based on these signs in puppies as early as 6 to 8 weeks of age.
There is no treatment for CEA.
Breeds affected: Australian Cattle Dog, Australian Shepherd, Bearded Collie, Border Collie, Boykin Spaniel, Collie, English Shepherd, Hokkaido, Australian Kelpe, Koolie, Lancashire Heeler, Windsprite, McNab, Nova Scotia Duck Tolling Retriever, Shetland Sheepdog, Silken Windhound, Welsh Sheepdog
References:
Parker HG, Kukekova AV, Akey DT, Goldstein O, Kirkness EF, Baysac KC, Mosher DS, Aguirre GD, Acland GM, Ostrander EA. Breed relationships facilitate fine-mapping studies: a 7.8-kb deletion cosegregates with Collie eye anomaly across multiple dog breeds. Genome Res. 2007 Nov;17(11):1562-71. doi: 10.1101/gr.6772807.
Gene: NHEJ1
Explanation of DNA Test Results
Normal (N/N)
This dog tested clear for the variant causing CEA in dogs. It can only transmit a normal gene to offspring and can be bred to a dog that has also tested N/N without producing affected offspring.
Carrier (A/N)
This dog has tested as a carrier for the variant causing CEA in this breed. It is at risk for developing the disease, and it may transmit either a normal gene or an affected gene to offspring. To minimize producing affected offspring this dog should only be bred to dogs DNA-tested NORMAL for this mutation.
Affected (A/A)
This dog has tested as affected for the variant causing CEA in this breed. It is at risk for developing symptoms of the disease. If this dog is bred, it will pass down the risk for developing IVDD to each of its offspring.
For more information on this disorder, please refer to the Canine Genetics Laboratory website https://cvm.missouri.edu/research/canine-genetics-laboratory/
Tests are ordered online through the secure area of the OFA website. Payment is accepted by credit card (MasterCard and VISA). The OFA administers all order handling. Upon receipt of an order, the OFA will send out the test kit which will include a Foam-Tipped Applicator card for DNA sample collection, along with sample collection instructions. Using the FTA card technology, owners can safely collect DNA samples at home. The collection process is non-invasive, and no veterinary appointment is necessary.
Samples are then sent to the University of Missouri College of Veterinary Medicine where the samples will be processed by the Small Animal Molecular Genetics Lab. Results will be forwarded to the OFA, and the OFA will issue the resulting report to the owner.
The fee for each test includes the test kit, laboratory processing, and subsequent registration in the OFA databases.